package cuiyt.algorithm.dfs;

import com.tencentcloudapi.yunjing.v20180228.models.MisAlarmNonlocalLoginPlacesRequest;

import java.util.Scanner;

/**
 * @author cyt
 * @create 2020-09-02 下午 4:04
 */
public class A {

    public static void main(String[] args) {
        A a = new A();
        Scanner scanner = new Scanner(System.in);
        int i = scanner.nextInt();
        System.out.println(a.getAns(i));
    }

    public int getAns(int n) {
        if (n == 1) {
            return 1;
        }
        if (n == 2) {
            return 2;
        }
        return getAns(n - 2) + getAns(n - 1);
    }
}
